Thomas Vermaelen has said he is in "a difficult situation" at Barcelona because of his lack of playing time.
Vermaelen has been called up by Belgium coach Roberto Martinez for this month's World Cup qualifiers despite not having played any competitive football for his club this season.
The 31-year-old former Arsenal defender has played just 11 La Liga matches for Barca since joining in 2014 because of a series of injuries, and played nine Serie A games on loan at Roma last season.
He attempted to convince Barca to allow him to leave in the summer but, when they refused, was left with his club career on hold.
"The club told me I couldn't leave in the summer despite interest from other clubs. I'm not playing so the situation is difficult," Vermaelen, who is not registered to play for Barca's reserve team, told reporters.
"I had to stay despite interest from other clubs. Now I'm not playing and so I'm in a difficult situation.
"I try to do extra training and stay positive, but you can't replace matches like that and I can't change anything for the moment.
"I can't play with the B team either, and that is, of course, regrettable."
He added that "in football, things can change very quickly -- a teammate can get injured, suspended."
And he said: "The World Cup and a January transfer are things to worry about later. We'll see, and I don't want to talk about it again.
"There is a significant transfer clause in my contract, even for a Premier League club."